Alloy



Patented Nov. 4, 1924.

UNITED STATES PATENT OFFICE.

COLIN G. FINK, OF YONKERS, NEW YORK, ASSIGNOR TO CHILE EXPLORATION GOM- PANY, OF NEW YORK, N. Y.,-A CORPORATION OF NEW JERSEY.

ALLOY.

No Drawing.

fl '0 all whom it may concern:

Be it known that I, COLIN G. F INK, a citizen of the United States, residing at Yonkers, in the county of Westchester, State of New York, have invented certain new and useful Improvements in Alloys; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to alloys and hasfor its object the provision of an improved alloy adapted particularly for withstanding attacks from corrosive liquors.

Metallic receptacles generally are not adapted for the handling of corrosive liquids because of the corroding or disintegrating effect which such liquids have upon the found an alloy of the following composi-,

tion to possess very excellent corrosive resisting properties: 11-13% silicon, 4.6% chromium, 46% manganese, 0.81.2% carcon, and the balance cobalt. The foregoing proportions may be varied in about the following percentages without material alteration of the desirable properties of this preferred form of the invention: silicon, 1015%, manganese 28%, chromium 242%.

In its preferred form, the principal constituent of the alloy of the invention is cobalt. However, I have found that the cobalt may be replaced to a certain extent by manganese or chromium, or .even by a small percentage of nickel, although the substitution of nickel for part of the cobalt is not recommendedtexcept where the cost of the alloy is an importantgfactor p: v osive jesistin Accord1ngly,,1

because.- nickeli Application filed January 26, 1921. Serial No. 440,167.

cobalt content of the alloy may be replaced a by manganese, or 5 to 12 parts (per 100 parts) of the cobalt content may be replaced by chromium, or 5 to 8 parts (per 100 parts) of the cobalt content may be replaced by nickel, without objectionably altering the advantageous properties of the alloy as a corrosion-resisting material.

As a result of my investigations and researches, I have found that an improved alloy resistant to corrosion from acid liquors, and in particular sulfuric acid liquors containing chlorides and nitrates, can be produced from cobalt and silicon, by combining these metals in the form of a cobalt-silicon alloy of appropriate composition. I have sesses other desirable qualities which adapt it particularly for use in the manufacture of corrosion-resisting receptacles, pipes, etc. I have, moreover, found that the addition of chromium, or other equivalent metal of the chromium group, such as tungsten, molybdenum or uranium, to the cobalt-silicon alloy imparts thereto furtheradvantageous characteristics.

I have found that commercial cobalt is well adapted for use in the production of a1 loys in accordance with the principles of the present invention. Cobalt has a marked affinity for carbon and,'if desired, may be preliminarily combined with the amount of carbon to be incorporated in the alloy. The proportion of carbon, of manganese, of chromium, and of silicon can be somewhat varied, but in general neither the carbon, the manganese, the chromium or chromium group metal, nor the silicon should be too low, since if these metals are not present in sufliciently large amounts the resulting alloy will not possess the desired corrosion-resisting properties. On the other hand, the carbon, the manganese, the chromium and the silicon content should not be too high. A high silicon content results in a decrease in the strength of the alloy and also increases the tendency of the alloy to corrode.

If; the carbon content is too high, the caron sena ates; l. 1 have p out -11 a ,gr ,th r

small amount of fine graphitic carbon, such as will give a grey surface to the fracture, but without any large excess of graphitic carbon.

I have found that the alloys of cobalt and silicon are distinguished from alloys' of other more or less similar metals with silicon in their availability for use as corrosion resisting materials. The advantageous properties of the cobalt-silicon allo s aredue, I believe, to the peculiar characteristics of these alloys. Microphotographssof cobalt silicon alloys containing about 12 to 15% of silicon indicate that the silicon is in part present as such or as cobalt-silicide (00 8i) in solid solution. in the cobalt, while a large part is present in the form of a eutectic made up of a mixture of cobalt silicide (Co Si) in the cobalt. The microphotographs indicate that the resistance to corrosion may be largely due to the presence of the silicon and of the cobalt silicide.

I have found that a maximum strength against flexure 'is'obtained when the silicon content of the cobalt-silicon alloy is about 12-15%. For example, a flexure strength of around 6200 pounds per square inch (unit .beam 1 inch square 12 inch span) has been possessed by alloys of this silicon content. Both any material increase and any material decrease in the silicon content of the alloy seem to decrease the mechanical strength of the alloy, and, in general, the greatest strength is obtained at between 12 and 15% of silicon. In its breaking strength, the improved alloy of the invention is to be distinguished from an alloy of iron and silicon,

'where, for example, a similar content of silicon gives an alloy with a flexure strength of Iabout 1000 to 1500 pounds per square inc I have obtained good results with a carbon content of about 1% or between 0.5% and 1.2%, and with a silicon content of from 12 to 15%. Graphitic carbon, as hereinbefore pointed out, is objectionable beyond a certain small amount, but inasmuch as cobalt will combine more readily than iron with a small amount of'carbon, it is possible to include such a larger amount in the alloy without an objectionable amount of graphitic carbon being present.

The proportions hereinbefore mentioned of the various ingredients of my improved alloy generally represent what I now believe to be the preferred form of-the invention.

' However, I wish it to be understood that these specific proportions mentioned may be somewhat varied without departing. from the spirit of the invention. Thus, for example, I have found that by increasing the silicon content up to about 20%, I can bring the manganese content as high as 45%. This is of particular advantage in that it tends to lower the cost of the alloy. In general, I

may say that an alloy embodying the principles of the invention in their complete aspect should contain from about 10 to 20% silicon, fromabout 2 to 45% manganese,

clusion of either manganese or a chromium group metal in the alloy that the presence of both of these metals is desirable, since their inclusion imparts to the alloy further desirable properties. Small percentages (up to about 4%) of iron, titanium, aluminum, antimony, bismuth, or tin, may be present in the alloy without objectionable impairing its corrosion resisting properties.

In the production of the improved alloy of the present invention, I may employ cobalt with its normal impurities, including some small percentage of nickel, iron, manganese and carbon. I have obtained good results with cobalt-containing around 4 to 7% of nickel and iron together. In the production of the alloy, I may proceed by melting the cobalt and adding charcoal thereto to increase its carbon content, or by simultaneously reducing a mixed oxide of cobalt,

manganeseand chromium (or other chro,

silicon or it may be combined with a small amount of cobalt, and the resulting alloy or mixture added to the remaining portion of the cobalt. This violent evolution of heat which takes place when the silicon is added to cobalt is a further characteristic of the cobalt-silicon composition which distinguishes it from iron-silicon compositions.

I claim 1. An alloy containing cobalt in predominant amount, and more than 10 and up to 20% of silicon. i

2. An alloy containing cobalt in predomi' nant amount, 10 to 20% of silicon, more than 2 and up to 45% of manganese, and 2 to 12% of chromium.

3. An alloy containing cobalt in predominant amount, about 12 to 15% of silicon and about 2 to 8% of manganese.

4. An alloy containing cobalt in predominant amount, about 12 to 15% of silicon, and

about 2 to 12% of chromium.

5. An alloy containing cobalt in predominant amount, about 12 to 15% of silicon,

about 2 to 8% of manganese, and about 2 to 12% of a chromium group metal.

6. An alloy containing cobalt'in predominant amount, manganese from 2 to 45%, chromium from 2 to 12%, silicon from 10 to 20% and sufiicient carbon to supply a small amount of graphitic carbon to the alloy.

7. An alloy containing cobalt in predominant amount, about 12 to 15% of silicon, about 2 to 8% of manganese and about 2 to 12% of a chromium group metal.

8. An alloy containing cobalt in predominant amount, 11 to 13% silicon, 4 to 6% chromium, and 4 to 6% manganese.

9. An alloy containing cobalt in predominant amount, 11 to 13% silicon, 4 to 6% of a chromium group metal, and 4 to 6% manganese.

10. An alloy containing cobalt in predominant amount, 11 to 13% silicon, 4 to 6% of a chromium group metal, 4 to 6% manganese, and 0.8 to 1.2% carbon.

In testimony whereof I afiix my signature.

COLIN G. FINK. 

